Napoli forward Hirving Lozano and goalkeeper David Ospina are both out injured, the Serie A club announced on Monday.
Mexican Lozano picked up a right hamstring problem in Saturday's 1-0 Serie A win over Juventus.
The 25-year-old, who has scored 13 goals in all competitions this season, could be sidelined for three weeks, according to Italian media reports.
Colombian international Ospina, 32, pulled a right thigh muscle during the warm-up for the weekend league game and could be sidelined for two weeks.
"The two players have started the rehabilitation process," Napoli added.
Gennaro Gattuso's side were already struggling with several injury and Covid-19 positives.
The pair will miss Napoli's Europa League last 32, first leg tie in Granada on Thursday, and Sunday's league clash at European rivals Atalanta.